Safety door mechanism for material elevator shaft



Aug. 28, 1956 J. A. MCBEATH SAFETY DOOR MECHANISM FOR MATERIAL ELEVATOR SHAFT Filed Feb. 20, 1 955 4 Sheets-Sheet 1 INVENTOR @Bfeaih BY V u K ATTORNEYS Aug. 28, 1956 J. A. MCBEATH 2,760,600

SAFETY DOOR MECHANISM FOR MATERIAL ELEVATOR SHAFT Filed Feb. 20, 1953 4 Sheets-Sheet 2 xi T n.) INVENTOR @2222 A..MBeai2z BY M (Tl, (a um-0L mm ATTORNEYS Aug. 28, 1956 J. A. MCBEATH 2,760,600

SAFETY DOOR MECHANISM FOR MATERIAL ELEVATOR SHAFT Filed Feb. 20, 1953 4-Sheets-Sheet 3 u L 1 ll 2 Q #0:: w H i in L \Q VJ IT g I Q R W INVENTOR Likm A. Mefieaih BY MAI/d2,

ATTORNEYS Aug. 28, 1956 .1. A. MOBEATH SAFETY DOOR MECHANISM FOR MATERIAL ELEVATOR SHAFT 4 Sheets-Sheet 4 Filed Feb. 20, 1953 INVENTOR Ji'm A cBeaih BY M W! W Mid-19m- ATTORNEYS hwy United States atent SAFETY noon MECHANISM non MATERIAL ELEVATOR SHAFT John A. McBeath, Atlanta, Ga

Application February 2 5 Ser al -33 5 Claims. (Cl. 187-61) The present invention provides improvements-in, safety locking mechanism for protecting personnel engaged in construction work of generally any type wherein lift .or hoist means are provided for lifting materials of .construction to a selected level on a building or other struc: ture being erected.

The need for a positively-acting safety mechanism in connection with such lifting means is emphasized by the fact that at least hundreds of workmen engaged in struc: tural work are killed or injured each year by. accidents involving the hoisting equipment. The present invention provides a simple safety mechanism .whieh is designed to eliminate the usually encountered and universally pres: ent hazards to the lives of personnel employed on .con: struction jobs which utilize the conventional type of hois.t. ing equipment.

The protection of such personnel is accomplished in accordance with the present invention by a safety lock assembly ,operatively associated with conventional ma: terial hoisting equipment. Such equipment includes gen: erally a platform hoist .or elevator for vertically transw porting materials of construction to a selected level. or succession of levels of a structure being erected, the. plat: form hoist or lift being operated in an openbraced four..- sided shaft positioned outside of the structure being erected. The platform lift is operated by a single cable attached to a single or double drum hoisting engine, which usually is located near the base of, the elevator shaft structure, or in some other location from which the operator cannot clearly view the shaft and theplab form lift, and consequently, for the operation thereof, dependence has to be placed .on a telephone, electric bell system, hand-pulled hell, or hand-given signals, ,by a person ,or persons, at various floorlevels, of the structural, job, or on the ground. The floor heights are painted on the hoisting cable, so that the engineer operating the en: gine, after receiving signals to lower or raise. the plat: form, moves it at a high rate of speed, the eng ne'being ope e W e a he single hoisting ab e ope at g the P t o a a h e oc y- W e ow r n the pla fo t e ee t s Off the rist n e ee. removes his foot from the brakes and drops the platform under f l v ty until a slow-down m r o he s b e a pears.- c e e a locking device of ndable sa e y s eces y to p n o m o s sk ns the r e ds. into the shaft to see where the platform is. Unless posi-. t m ns o P e e u p a a e Provided it s em to be a part Of hu f n s o workmen t do 0, there resulting a great number of fatalities caused by the platform hitting the workmen on the heads,

One of the principal objects of this inyention is the provision Of a a ty o o he PI t-QQQF 9 the M33- men at different levels, and safety locking instrumentalb ities for each door that are so constructed that each door released opens only when the platform is going up and is brought to a complete stop at the desired floor level, the locking instrumentalities permitting the platform to be lowered at any rate of speed with 'no disturbance of the ice 2 locked setting of the instrumentalities during the descent of the platform.

In erecting building structures it is necessary to have adjacent thereto an elevator shaft and a platform elevator or hoist adapted to travel therein for delivering materials to respective floor levels of the structure, and one of the principal objects of this invention is the provision of a door and locking assembly mounted on the shaft structure at each floor level ofthe building and adapted to maintain said door normally locked, and meanscarried by the elevator and coacting with said assembly for releasing said locked door upon stopping of the elevator at any desired floor level.

Another important object of this invention in connection with the erection of a building structure and including an elevator shaft having an elevator movable in the shaft, is the provision of a safety door and a mechanism mounted on said shaft normally locking the door in closed position at each floor level of said structure, means carried by the elevator coacting with said mechanism to release the door at any desired floor level upon stopping of the elevator at said level, construction of said mechanism being such that the operation during the upward travel of the elevator is ineffectual to release said doors, unless the elevator is brought to a complete stop at a desired floor level, and therespective mechanisms are not operated at all .during the travel of said elevator in descending direction, so that to stop at a desired floor level the elevator is halted below said level and returned in an upward direetion to said level, and as it is brought to acomplete stop the locked door is released, permitting the door to be opened.

Another important object of this invention, in connection with a building structurebeing erected with a plurality of floor levels and a shaft having an elevator movable therein, is the provision of a normally locked door including a latch keeper and a locking mechanism coacting therewith and with a cam carried by said elevator, said mechanism including a latch member engageable with said keeper, a spring controlled pivotally mounted arm, the construction of said arm being suchas to retract said latch from door locking position upon engagement of said cam therewith when the elevator is moving in ascending direction, but the latch locking position of said arm is not disturbed by said cam during the downward movement of said elevator, so that none of the door locking mechanisms are disturbed during the downward travel of the elevator. I i

A further important object of thisinvention, in connection with a material platform hoist, is the provision of a safetyv door and locking means therefor, including a latch receptor or keeper carried by the door and a latch mechanism including a latch member, and a cam actuated spring controlled roller arm means engageable with said latch member, said roller arm means positively forcing said latch into latching engagement'and locking the latch therein until the arm is moved into locking position by upward movement of the platform cam, the construction of said cam arm being such that a downward movement of the cam does not actuate said arm to retract the latch, and should the control spring break, and drop down, said roller arm still would retain the latch in door locking position. v

A further object of this invention is-the provision of a material lift elevator structure safety door locking assembly at each floor level automatically operable by the lift when moving in ascending direction, and whencoming to a stop at a desired floor level, and so constructed as to be positively locked, preventing accidental unlocking thereof, and so constructed that ice or debris do not cause operating parts to jam or cease tooperate.

Further objects of this invention will become apparent as the description proceeds, and the features of novelty will be pointed out in particularity in the appended claims.

The structural details and operation of the improved construction are illustrated in the accompanying drawings, which illustrate a representative embodiment of the improvements comprised in the safety mechanism of the present invention.

Referring to the drawings, it is noted that:

Fig. 1 represents diagrammatically a side elevation of a hoisting installation embodying the present improved construction.

Fig. 2 is a side elevation of a lock assembly embracing the improved features of the present invention.

Fig. 3 is a top plan view of the assembly of Fig. 2.

Fig. 4 is a side elevation of the locking assembly with the locking element in opened position.

Fig. 5 is a front elevation of the assembly, the view being taken on the line 5-5 of Fig. 4, looking in the direction of the arrows.

Fig. 6 is a longitudinal sectional view of the lock assembly, with the platform hoist in down position.

Fig. 7 is a fragmentary view of a spring employed for return of a rear roller employed in the assembly.

Fig. 8 is a top plan view of the safety lock assembly and door, corresponding corner posts of the elevator shaft structure being shown in section, the view indicating the mounting of the safety lock assembly and door on these corner posts.

Referring more particularly to the drawings, reference character A is used to designate a vertically operable elevator which runs in an open braced four-sided shaft B that extends the height of a building C being erected. This building has a plurality of floor levels D, a removable runway B being provided each floor level D, there being such a runway extending from each floor level to the shaft B. The elevator A, which is provided to deliver materials of construction to any selected floor level, is operated by a single operating cable which is attached to the elevator and passed around a winch G driven by a source of power H in a remote location K. The cable F passes around a bottom pulley sheave L and top pulley sheaves M and M mounted in the top shaft frame structure B.

The safety provisions of the present. invention comprise a door I mounted adjacent to the shaft B at each floor level so as to close access to the shaft from each runway E. Associated with each door at the top are safety locking instrumentalitics which are momentarily and inefiectually releasable responsively to the elevator A reaching the successive floor levels, but which lock automatically as the elevator A moves past the respective floor levels, and which remain locked during downward travel of the elevator A, so that workmen cannot endanger themselves by sticking their heads into the shaft while looking for the position of the elevator car or platform. Many fatal accidents have occurred from this cause, it being apparently a commonplace practice on the part of workmen to do just that, notwithstanding the obvious danger, as the inside of the shaft is not visible to an engineer at the remote operating station, which conventionally is a shed in which the operating winch G for the hoisting cable F and the engine H are located. Lifting of the elevator A is effected by winding the cable F on the reel of the winch G by power applied from said engine. When the elevator A has been unloaded and ready to descend, the winch is disconnected from the engine by clutch mechanism, not shown, and the brakes of the winch are released so that the elevator A falls freely by gravity through the shaft. The highvelocity falling of the elevator renders it likely that any workman loses his head whenever he may resort to the extremely hazardous practice of sticking his head into the shaft to see the location of the elevator.

Each of the doors 1 is movably mounted for opening and closing access to the elevator shaft B, on brack or supporting arms 2, mounted on a corner post of the elevator shaft, the mounting 3 hinging the door for its movements on arms 2. Instead of being hinged, as shown at 3, it obviously may be mounted for sliding or lifting movement, the important provision being that none of the doors can be opened except by release of the improved safety lock by the elevator reaching and stopping at a selected floor level during the upward movement of the elevator. The improved safety mechanism is the same for each door, so that only one of the doors and its associated locking assembly need to be described in detail.

For such description, reference may be made particularly to Figs. 2 through 5, which show the structural details of any one of the safety doors and its associated safety locking instrumentalities, these views indicating the operation of such instrumentalities during upward movement of the elevator A for releasing the said instrumentalities for permitting the door to be opened when the elevator A is raised to, and stopped at, a selected floor level.

As will be seen from these views, the door 1 preferably is a steel door, so that a mounting 4 for a latch keeper or receptor 5 may be welded to its inner surface facing the elevator shaft B. The welds for the mounting 4 (which is suitably a steel plate), are indicated at 6, and those of the keeper 5 are indicated at 7, the latch receptor 5 is a hardened steel cup-like member having a latch receiving recess 8 therein, the bottom of which slopes inwardly and downwardly as shown in Fig. 6, for receiving a complementally formed latch portion of the latch member N as will be apparent from Fig. 6, which latch member is a part of the locking instrumentalities which now will be described.

The recess 8 in the keeper 5 is adapted to receive the downwardly hook-like portion 11. It will be noted that the latch member N comprises an arm or body portion 9 formed at its upper end with a right angular forwardly projecting portion 10 formed with said downwardly inclined hook-like end portion 11 adapted to lockingly extend in the recess 8 in locking engagement with the complementally inclined seat 5 in the latch keeper 5 for effecting a positive locking of said door in closed position. The arm 9 is formed at its lower end with a right angular rearwardly extending bell crank-like arm 11 and is pivoted at its lower end on shaft 12 that is mounted in spaced parallel horizontally extending arms 13, which project horizontally from the lower ends of vertical standards 14, which in turn are carried by corner post 15 of the elevator shaft structure B by means of a bracket arm 16, secured to the post 15 by means of screws 17, extending into the corner post through flange 18 of bracket arm 16, and bracket arms 2 of the door are secured to the corner post 15 by screws 17'. The locking latch arm 9 serves as a mounting for a rear abutment cam 19 having a cam surface 20 which is engaged by an end roller 21 mounted between bifurcated arms 22 of the inner end of actuating lever 23, the roller 21 turning on an axle shaft 24 extending through the said arm portion 22.

The latch operating arm 23 is a lock-actuating lever, mounted on fulcrum shaft 25 which is mounted in the vertical standards 14, one end of the lever 23 is welded, as is indicated at 26 to spaced parallel arms 27, these arms form a continuation of said arm 23. The shaft 25 extends through one end of these arms and the end of the solid portion of arm 23, said arms 27 define an end extension for the latch lock-actuating lever arm 23, the spacing between these arms 27 being equal to the thickness of the arm 23.

Extending through these arms 27 is a pivot shaft 23 on which is mounted spaced parallel arms 29 which are maintained spaced apart by a spacer block .30 that is welded to the arms 29, as is indicated at 31. The arms 29 are pivoted on said pivot shaft 28 and are adapted to move independently of the arms 27 and latch lever greases 3 arm 23 in one direction, as will be pointedfoiit hereiriaft'er. -It will be apparent from the above descriptionthat the arms 29 form a depressib'le 'arinjportioh 23' of'arm 23. An end roller 32 ismountedfbetween the 'free ends of arms 29 on axlefshaftf33 which extends through the arms 29 "andjperiphferally iprojects bieyond the end of these *arms for "a purpose set "forth hereinafter. V v v A stop 34 is welded to the vertical uprights 14 and extends across the latch-actuatingarm 23, this stop 34 being an abutment for limiting upward pivo'tal movement of the arm 23 under pulls thereon exerted by tension of a coil spring'35,"oneendof which'issecured in an eye-screw 36 extending from the top of farm 23, the opposite end of whichis secured 'to a screw 37 extending into a cross piece '38 which is welded to the uprights 14 at a suitable distance above abutment stop 34 to produce a desired tension in the spring 35.

The spring 35 continuously urgeslthelarm '23 towards and against the stop 34, this stop holding the arm in horizontal position except when snfiicient force is 'exerted against the outer end of the arm to overcome the holding tension of the spring 35 for depressing the arm about the pivot shaft 25 until the periphery of roller '21 which extends beyond the ends of arm portion 22 of the arm 23 is pressed against a trigger arm 11 of the latch N'for actuating said latch and for retracting latch portion 11 from looking engagement with seat-5 in the recess 8 of thenlatch-keeper 5, n

n A second-stop 39 is welded 'to the top 'Of one-orboth of the arms 27 and projects overfat least one of the end arms 29 for limiting upward pivotal movement of the arms 29 and roller 32 relative :to the arms 27 and arm 23, the arms 29 being continuously urged toward andagainst the abutment stop 39 by tension offa spring 40 (Fig. 7) which is held .under tension between axle shaft 28 and a pin 41 in an arm 27 (Fig. 3). The arms 29 form the pivoted end section 23' and therefore are free to pivot downwardly independent-lyof the arms 27 when the roller 32 is depressed sufiiciently to'overcome the tension of the spring 40, as is shown --in;F ig. 6, but is prevented from being lifted by the tension of spring 40 to any position above alignment -of.the arms 29 with arms 27 and arm 23, so that lifting forces exerted against roller 32 will move the arms 29, and arms 27, and arm 23 as a rigid unitary structure or assembly for depressing the inner end of arm 23 carrying the roller 21 until this roller engages the trigger of ,trip arm 11 of the latch N forretraction of the locking latch portion 11 from the locked recess 8. s

From the foregoing description it will be seen that the safety provisions of the presentinvention -comprising a door located at various floor levels of a'buildiii'g being erected for blocking access to an open-braced elevator shaft containing a traveling elevator that is provided for delivering materials of construction'to one or more selected floor levels, there being mounted on the side of the door facing the elevator shaft, that is referred to herein as the inner surface of the door and adjacent to the top thereof, a recessed cup-like latch receptor or keeper which receives a latching or locking means for the door, which means comprise a locking latch member having oppositely directed arms which extend oppositely and in substantial parallelism from an approximately upright connecting lever member, so that one of the arms is an upper arm terminating in a locking latching portion which releasably engages the locking keeper on the door, the other of the arms being a lower actuating or trigger arm intended to trip the locking means for releasing the locking latch portion from the keeper or receptor, the locking means being pivotally mounted in a mounting bracket struc- -ture, the lower or trigger arm'of the locking means being below and engageable by an operating lever arm, which normally is approximately horizontal, but which [operating-arm rocking vertically on its p vo mou "arm "for independent movement relative thereto in one direction of vertical displacement, but 'bei'ngpr'dV' is applied in the 'opp'o'site direction; thatfis to 'bly of an operating arm and"the"saidouter"'ehdse on,

"of the latch portion 'to depress "the trigger to withdraw the latch portion from locking element of the locking latch N downwardly-directed force is applied to outer, -e rid of from its locking position. leas'ed during application I of an upw locked responsively to :"iIs 'v ir y fi h i fin? and being spring-returned 'to nornial'hor ,1 ti-on after being rockinglyd'isplaced therefr m it its pivot, 'this operating arm terminating infan outer section which is p'ivotallyfmounted on the ppferati v Y. Med with'stop means 39, similar to stop ean'fsf3fqt exte it; over andacross said arm for holdlngt endfsect rigid with the operating arm when di c'ing c'e hen the outer 'end of "the operating arm, whicl is ana'sseinisacted upon by an upwardly directedfor'cethe 'pi outer end section formsa rigid contin njoflhe op' ating arm and causes th' inner end thereof fo bfe placed downwardly against thle lower'or jtrigger the operating assembly, the pivoted je'nfd "sec" i1 is ,depressed without affecting the locking positioh df thfe mechanism, and without releasing the locking lat'i ih Therefore, "the ,IjdQor is is; dly directed, ffofe vr n semb hifi erelease of the upwalfdl directed force, and maintained locked duringffappl ationlfof against the 'outer end of the op downwardly directed forces to the outer end of the operating assembly. v v v n In "the practical application ofjthe abov deserted safety mechanism, the upwardly and dhw wardiy Tajirected forces applied to the actuating a sseiriblyfarerpro vided by the upwardfand jdowr'i'wa'rdihove'fr iel lfs off-the elevator A, it being the i-ritehtionfthfan only the idea; at a select'edfloor level be released and openable while the elevator is stopped in working position at thatpar- 'ticular selectedfioorlevel, all other doorsrbeingfllocked continuously, and the selected, ldoo'r being re-ldckedirri- 'mediatey upon the elevator being lifted or l'oweredffr'om working position at the, said selected floor level, amiau doors remainingloc'ked through the entire descending travel of the elevator- A; l

In order to accomplish this, there ism'ou'nte d, in the present instance, on a suitable steel frame, structurefb attachedto the edge of the elevator platform A; fa cing the door 1, which extends u to whath may -be termed the top of the elevator, and thenacross "to the cylindrical bar P to which said'frame is welded on otherwisesecured, said bar at each end being connected to the platform supporting elements Q, and welded or otherwise securedt o the front of said framestructu re Q-is an elongatedabutment cam 42 which extends above the elevator-and which engages the outer end roller ,32-on the operating assembly. I In order to enable therollerjZ t0 ride hn the abutment 42, the latter is provided with oppositely inclined top and bottom v camsurfaces 43 and 4,4, respectively, the top cam surface 43 lifting -;the roller Y132 and operating assembly -until.-the roller rides on the elongated plane abutment-surface 45 intermediate the cam surfaces 43am 4'4, and, theinner'end of the'ope'rating assembly is moved until the roller 21 thereon engaged the trigger arm 11' of the loekinglatch and the locking latch portion 11 -is withdrawn hr, "e recess 8, thereby unlocking the door. Obviously, the "oil spring 35 is stretched during this unlocking action, the operating arm 23 and the outer end section 23 thereof acting as a, rigid integral unit. When the elevator A moves upwardly until the roller 32 reaches the lower cam surface 44, thereby releasing the operating assembly for the locking means, the spring 35 immediately returns the operating assembly, with the inner end roller 21 engaging first the bottom cam surface 20 of abutment cam 19 on the upright arm 9 of the locking latch N, thereby forcibly holding the latch end 11 in locking engagement with the locking recess 8. The stop 34 preferably extends across said arm 23 and properly limits the upward or return movement of the operating assembly.

It will be apparent from the foregoing that each door that is passed by the elevator A during ascent thereof is released successively during the time interval that the roller 32 of each locking mechanism is in engagement with the plane surface 45 of the abutment cam 42. However, as will be apparent also, unless the elevator A is stopped at a given floor level, such release of the doors is only of momentary duration, each door being automatically relocked as soon as the cam 42 moves from engagement with the respective roller 32 and before any door can possibly move or be moved from closed position.

During the descent of the elevator A, each roller 32 engages the bottom cam surface 44 of the elevator cam 42, thereby displacing the outer pivoted end section of each successive operating assembly downwardly, but without disturbing the locking position of the remaining parts of the mechanism. The downward displacement of the end section stretches the return spring 40, which snaps the end section back into normal position against stop 39.

From the foregoing, it will be apparent that if it should be desired to stop the elevator A at any given floor during its descent, it is necessary to drop the elevator completely below that floor level until the roller 32 clears the cam 42 and then to raise the elevator to that selected floor level in order to actuate the mechanism for unlocking the door at that level; and as pointed out above, such door remains unlocked as long as the elevator is stopped at such level, with the roller 32 resting on the plane surface 45 of the cam 42.

The present improvements therefore provide positive safety equipment for preventing serious or fatal accidents to building workmen at elevator shafts during building operations.

If desired, there may be provided on the elevator shaft B for each floor level, an electrical light switch 46 connected in series with a master light, illuminated panel or the like 47 in the elevator operators shed or station K, each switch being actuated by the elevator A during up and down travel thereof, so that an operator can know the location of the elevator at all times. This is a conventional installation and requires no further description.

This is also equally adaptable as a means of signaling the operator to stop at a particular floor level.

By placing the safety locking instrumentalities adjacent to the top of each door and mounting the same from corner post 15 of the elevator shaft B, the runways E are unobstructed for delivery of structural materials from the elevator A, when the selected door 1 is open.

Although in practice it has been found that the form of the invention illustrated in the accompanying drawings and referred to in the above description as the preferred embodiment is the most efficient and practical, yet realizing that conditions concurrent with the adoption of the invention will necessarily vary, it is well to emphasize that various minor changes in details of construction, proportion and arrangement of parts, may be resorted to within the scope of the appended claims without departing from or sacrificing any of the principles of this invention.

Having thus described the invention, what is desired protected by Letters Patent is as set forth in the following claims- I claim;

1. In a building under construction having a plurality of floor levels, the combination which comprises a substantially open elevator shaft having spaced corner posts, an elevator operable in the shaft for handling materials of construction, a runway at each floor level interconnecting each floor level with the shaft, control means for the elevator operable from a station remote from the elevator for stopping operation of the elevator at a selected floor level fordelivering and receiving materials of construction at the selected floor level, spaced upper and lower armsextending forwardly from one of the corner posts, a normally locked safety door hingedly connected to said arms for each runway and remotely spaced from the shaft and blocking the runway when the door'is in normally closed and locked position for preventing access to the shaft, locking mechanism for the door intermediate the door and shaft and inoperable from the runway, the locking mechanism for the door including a retractable latching member for the door inoperable from the runway, said latching member having an angular lever portion at its lower end, bracket arm means extending forwardly from another corner post, a mounting frame carried by. said bracket arms having substantially upright and horizontal portions, the latch member being pivotally mounted intermediate said horizontal portions of the frame, lever actuating means pivotly mounted on the upright structure of the frame, and one end engaging the latching member for the door, a cam member on the elevator engaging the other end of the lever actuating means for shifting the said lever actuating means into releasing position for the latching member for retracting the latching member from the door responsive to upward movement of the elevator, and snap-acting tensioningmeans operably connected to the lever actuating means and to the upright frame structure for immediately shifting the lever actuating means against the latching member for forcibly securing the latching member in latching position against the door immediately responsive to disengagement of the cam member from the lever actuating means, the said lever actuating means being unafiected by the cam member during downward travel of the elevator.

2. In a building under construction having a plurality of floor levels, the combination which comprises an elevator shaft having spaced corner posts, an elevator operable in the shaft for handling materials of construction, a runway at each floor level interconnecting each floor level with the shaft, a normally locked door for the runway blocking the runway when in locked position and preventing access to the shaft, the door being spaced from the shaft and intermediate the shaft and floor level and having a side normally facing the shaft, mounting means for the door carried by a corner post of the shaft, and cuplike latch keeper having a latch receiving recess therein and which is rigidly carried by said door, releasable locking mechanism for the door intermediate the door and shaft and positioned on the side of the door facing the shaft and hence inoperable from the floor level and runway, said locking mechanism including a mounting frame having spaced parallel arms and vertical standards carried by supporting means rojecting from a corner post of said shaft, a latch member having a body portion formed with an angular projector engageable in said cuplike keeper and an oppositely projecting lever portion, said member being pivotally mounted on said spaced arms, a cam member on the elevator, a pivotally mounted latch operating arm, means included in the locking mechanism for the door engageable by the cam member for releasing the door during upward travel of the elevator and cam member, and quick-acting spring means operably connected to the cam-engageable means and to the vertical standard structure for restoring the locking mechanism into locking position for the door immediately responsive to disengagement of the cam member from the said cam engageable means.

3. In a building under construction having a plurality of floor levels, the combination which comprises a substantially open elevator shaft spaced from the building, a runway extending from each floor level to the shaft, a door for each runway spaced from the shaft, mounting means for the door carried by the shaft, a latch-locking cup-like receptor carried by the door and having its bottom surface inclined downwardly and inwardly, an elevator operable in the shaft, a cam carried by the elevator, a substantially L-shaped supporting frame structure mounted on and spaced from the shaft, a locking-latch member pivotally mounted on the frame and having a complementally inclined hook end engageable in releasable locking engagement with the bottom of the receptor, a cam-engageable arm member pivotally carried by the frame structure and normally maintaining the hook end of the latch member in locking engagement with the latch receptor on the door, spring means connected to said arm and to said L-shaped frame structure, the said arm member being operable by engagement of the cam therewith when the elevator is stopped at a selected floor level to effect door-unlocking retraction of the latch member, the arm-member returning the latch member to door-locking engagement with the receptor on the door by the action of said spring upon disengagement of the cam from the arm member.

4. In a building under construction having a plurality of floor levels, the combination which comprises a substantially open shaft spaced from the building, an elevator operable in the shaft, a runway extending from each floor level to the shaft, a normally latched safety door for each runway spaced from the shaft, mounting means for the door carried by the shaft, a latch receptor having a cam locking surface carried by the said face of the door on an upper portion thereof, a supporting frame structure mounted on and spaced from the shaft and including a bell-crank latch member, the said latch member including a long latching arm having an upper end terminating in a latching hook entering the receptor in latching engagement with the cam locking surface of the receptor, and a short actuating arm at its lower end, a pivotal mounting connecting said latch member to the frame structure at the inner end of the short arm member, the latch member being freely rotatable on the pivotal mounting, a cam engageable arm pivotally mounted on the frame structure, one end being a shaft end, and the opposite end of said arm being engageable with said latch member, the shaft end extending from the pivotal mounting to the shaft being the longer and overbalancing end normally tending to retain the latch end in engagement with the long arm of the latching member for urging the latching hook into latching engagement with the locking cam surface of the receptor, said cam engageable arm having a short section adjacent its cam engaging end being movable only in a downwardly direction with respect to the arm proper, a cam carried by the elevator engageable with the shaft end of said arm for shifting this arm responsively to the upward travel of the elevator and cam until the latch engaging end is forcibly depressed from said long latching arm of the latch member into pressure engagement with the short arm thereof, thereby retracting the latching hook from the receptor for releasing the door and so maintaining it as long as the elevator is stopped at a floor level, and as the cam is disengaged from the end of the arm, its opposite end moves up the long latch arm returning the latch hook to locking engagement with the receptor cam, and means for accelcrating such return movement of said arm, the downward movement of the elevator and cam merely depressing said movable arm and section.

5. The structure of claim 4 wherein the long latching arm of the latching member is provided with a cam normally engaged with the latch-engaging end of the arm member to positively lock said locking member, and a tension spring connected to the frame structure and to the arm intermediate the latch engaging end of the arm member and the pivotal mounting of the arm member on the supporting frame structure for effecting a quick return of the said arm member to its normal position responsive to disengagement of the elevator cam with the shaft end of the arm during upward travel of the elevator and its cam, such upward travel of the elevator and elevator cam lifting the shaft end of the arm member, and correspondingly depressing the latch-engaging end thereof with corresponding increase in tension in the spring until the latch-engaging end of the arm is shifted from engagement with the cam on the long arm of the latching member into forcible engagement with the short arm of the latching member for turning the latching member around its pivotal mounting until the latching hook thereon is retracted from its latching engagement with the receptor on the door, the movable end section of the elevator cam engageable arm being pivotally mounted and spring controlled, downward movement of the elevator and cam thereon merely depressing the movable shaft end section of the arm member without disturbing the remaining portion of the arm and its locking engagement with the latch structure.

References Cited in the file of this patent UNITED STATES PATENTS 1,162,799 Mutton Dec. 7, 1915 1,273,570 Blessing July 23, 1918 2,671,531 Homstrom Mar. 9, 1954 

